Chapter 7 Troubleshooting and Maintenance

Monitoring the Voice Quality of Calls

Step 2 While the phone is powering up, press and hold # button until the Line LED turns green. Step 3 Release the # button and press 123456789*0#.

The line button LED turns red. The phone reboots when it is finished.

Monitoring the Voice Quality of Calls

To measure the voice quality of calls that are sent and received within the network, Cisco Unified IP Phones use these statistical metrics that are based on concealment events. The DSP plays concealment frames to mask frame loss in the voice packet stream.

•Concealment Ratio metrics—Show the ratio of concealment frames over total speech frames. An interval conceal ratio is calculated every 3 seconds.

•Concealed Second metrics—Show the number of seconds in which the DSP plays concealment frames due to lost frames. A severely “concealed second” is a second in which the DSP plays more than five percent concealment frames.

•Mean Opinion Score (MOS) for Listening Quality (LQK) Voice Metrics—Uses a numeric score to estimate the relative voice-listening quality. The Cisco Unified IP Phones calculate the MOS LQK based audible-concealment events due to a frame loss in the preceding 8 seconds and includes weighting factors such as codec type and frame size.

MOS LQK scores are produced by a Cisco-proprietary algorithm, the Cisco Voice Transmission Quality (CVTQ) index. Depending on the MOS LQK version number, these scores may comply with the International Telecommunications Union (ITU) standard P.564. (This standard defines evaluation methods and performance accuracy targets that predict listening quality scores based on observation of actual network impairment.)

Note Concealment ratio and concealment seconds are primary measurements based on frame loss. A Conceal Ratio of zero indicates that the IP network is delivering frames and packets on time with no loss.

You can access voice quality metrics remotely by using Streaming Statistics (see the Monitoring the Cisco Unified IP Phone Remotely chapter).

Using Voice Quality Metrics

When using the metrics for monitoring voice quality, note the typical scores under normal conditions of zero packet loss and use the metrics as a baseline for comparison.

It is also important to distinguish significant changes from random changes in metrics. Significant changes are scores that change about 0.2 MOS or more and persist in calls that last longer than 30 seconds. Conceal ratio changes indicate a frame loss greater than 3 percent.

The MOS LQK scores can vary based on the codec that the Cisco Unified IP Phone uses. The following codecs provide these corresponding maximum MOS LQK scores under normal conditions with zero frame loss for Cisco Unified Phones 6921, 6941, and 6961:

•G.711: 4.5 MOS LQK

•G.722: 4.5 MOS LQK

 

 

Cisco Unified IP Phone 6901 and 6911 Administration Guide for Cisco Unified Communications Manager 8.5 (SCCP and SIP)

 

 

 

 

 

 

OL-23874-01

 

 

7-11

 

 

 

 

 

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Cisco Systems 6901 manual Monitoring the Voice Quality of Calls, Using Voice Quality Metrics
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6901 specifications

Cisco Systems 6901 is a versatile, compact, and powerful router designed to meet the networking needs of small to medium-sized businesses, as well as enterprise branch offices. This model is part of Cisco's ISR (Integrated Services Router) portfolio, which is known for its capability to integrate multiple services into a single platform, ensuring high efficiency and cost-effectiveness.

One of the main features of the Cisco 6901 is its ability to support advanced routing protocols, including RIP, EIGRP, OSPF, and BGP. This versatility allows for seamless integration into various network architectures, facilitating efficient communication and data transfer across multiple locations. The device is also built to handle high-bandwidth applications, making it an ideal choice for businesses that rely on robust network performance.

In terms of connectivity, Cisco 6901 offers multiple Ethernet ports, supporting both 10/100/1000 Mbps speeds. This ensures that users can connect a variety of devices, ranging from office computers to network printers, all while maintaining optimal network performance. Additionally, the router supports both LAN and WAN interfaces, providing flexibility in deployment options.

Security is a crucial aspect of networking, and the Cisco 6901 does not disappoint in this regard. It comes equipped with advanced security features, including firewall capabilities, intrusion prevention, and VPN support. These features ensure that sensitive business data is protected from unauthorized access, while also providing secure remote access for employees.

Another essential characteristic of the Cisco 6901 is its support for various multimedia applications. The router comes with Quality of Service (QoS) features that prioritize voice, video, and data traffic, ensuring high-quality performance for applications such as VoIP and video conferencing. This is particularly valuable in today's business landscape, where effective communication is critical for success.

The Cisco 6901 is also designed for ease of management and configuration. It features a user-friendly interface that simplifies the setup process, along with comprehensive monitoring tools that enable administrators to keep an eye on network performance and address any issues proactively.

In summary, the Cisco Systems 6901 is a powerful, feature-rich router that combines advanced routing capabilities with robust security measures and multimedia support. Its flexibility, ease of management, and comprehensive service integration make it an excellent choice for businesses seeking to enhance their networking infrastructure. With the Cisco 6901, organizations can achieve efficient communication, secure data exchange, and high-performance network operations, positioning themselves well for future growth.
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